[urq] Vacuum Leaks and the Diff Lock Actuators

[Andrew Finney]

Excuse the rambling.......

I just replaced my center differential lock actuator this weekend
(mine has been converted to the later 4000Q-style rod and up-front
actuator for faster action) to eliminate a funky whoosing noise during
idle. As suspected, the actuator was the culprit. I had previously
determined that only 1 of the 2 ports held vacuum. Now that I
dissembled the actuator, I can see the weak point on these things. The
exterior rubber sleeve is not just designed to keep dirt and moisture
out of the actuator, if it rips, it introduces a leak that is only an
issue when the diffs are not actuated (most of the time). So, try
pulling a vacuum on both side of your actuators, both sides must hold
vacuum, if not you have a vacuum leak, likely at idle. When you fix
the leak you'll be amazed at how much faster the diffs actuate and
deactivate because release of the diffs is aided by the constant
application of vacuum on one side of the diaphragm.

I also checked out Mercedes parts while at the bone yard. As far as I
can tell, while the door lock actuators from a Mercedes are similar in
appearance to our actuators, they only have one port. This means
you'll need to apply pressure, not vacuum, to the single port to
reverse the operation. In the future I'm going to rig up a system
using these parts and the pumps for our door lock actuators.

Does anyone know of a source for the exterior rubber sleeves on our
the actuators.... some other application that can be made to fit?

Andrew Finney
1983 and 1984 UrQs.